Polyamide materials, in particular nylon fibers and yarns, are of great value in the textile industry. It is well known that such materials are typically receptive to acid (anionic) dyes but have practically no affinity for basic (cationic) dyes. This latter characteristic is a disadvantage in that basic dyes are known to impart brighter shades than acid dyes to textile materials. Thus, normally only certain types of color effects, consistent with the characteristics of acid dyes, can be produced on typical, untreated polyamide textile materials. Thus, it is desirable to produce polyamide textile materials that have increased receptivity to basic dyes.